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在以为中心的S_N2反应中非传统的途径:从圆圈到化物转移

Siddharth Sankar Dutta¹, Upakarasamy Lourderaj¹

¹School of Chemical Sciences, National Institute of Science Education and Research (NISER) Bhubaneswar, An OCC of Homi Bhabha National Institute, P.O. Jatni, Khurda, Odisha 752050, India.

The journal of physical chemistry. A

|November 19, 2024

概括

这项研究揭示了以为中心的双分子核替代 (S_N2@N) 反应中意想不到的主导的质子转移和新型化物转移途径. 还确定了漫游等非常规机制,挑战了以前对S_N2动态的理解.

科学领域:

化学动力学化学动力学
反应机制反应机制
计算化学的计算化学

背景情况:

双分子核替代 (S_N2) 反应是化学的基础.
了解碳以外的中心的S_N2反应,例如 (S_N2@N),对于扩大化学反应知识至关重要.
之前的研究主要集中在碳中心的S_N2反应上,使得以为中心的反应得到了较少的探索.

研究的目的:

研究在中心发生的S_N2反应的复杂机制和动态.
使用先进的计算方法探索胺 (NH₂Cl) 和甲氧化离子 (CH₃O^-) 之间的反应.
在S_N2@N反应中识别和描述新的反应途径和机制.

主要方法:

从一开始,使用经典轨迹模拟来建模反应动力学.
用MP2 ((fc) / aug-cc-pVDZ理论水平进行高精度的电子结构计算.
模拟结果与实验数据进行了比较,以验证.

主要成果:

观察到预期的S_N2产物 (CH₃ONH₂ + Cl^-),但发现产生CH₃OH和NHCl^-的高能质子转移途径占主导地位.
确定了一种新型的化物转移通路,产生NH₃,H₂CO和Cl^-,表明新的反应道.
除了传统机制外,还发现了一些非常规的机制,包括漫游中介和绕道路径.
一部分轨迹显示NH₂组的逆转,导致CH₃ONH₂产品保留配置.

结论:

以为中心的S_N2反应表现出复杂的动力学与主导的非S_N2路径,如质子转移.
新的反应通道,如化物转移,存在于S_N2@N反应中,扩大了已知的反应范围.
这项研究强调了考虑非传统机制的重要性,并提供了对S_N2@N反应动态的更深入的理解.

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